[PATCH 2/2] OvmfPkg/PlatformPei: DENY_EXECUTE_ON_SECURITY_VIOLATION when SEV is active

[Brijesh Singh <brijesh.singh@amd.com>]

The following commit:

1fea9ddb4e3f OvmfPkg: execute option ROM images regardless of Secure Boot

sets the OptionRomImageVerificationPolicy to ALWAYS_EXECUTE the expansion
ROMs attached to the emulated PCI devices. A expansion ROM constitute
another channel through which a cloud provider (i.e hypervisor) can
inject a code in guest boot flow to compromise it.

When SEV is enabled, the bios code has been verified by the guest owner
via the SEV guest launch sequence before its executed. When secure boot,
is enabled, lets make sure that we do not allow guest bios to execute a
code which is not signed by the guest owner.

Fixes: https://bugzilla.tianocore.org/show_bug.cgi?id=728
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 OvmfPkg/OvmfPkgIa32X64.dsc          | 9 +++++----
 OvmfPkg/OvmfPkgX64.dsc              | 9 +++++----
 OvmfPkg/PlatformPei/PlatformPei.inf | 2 ++
 OvmfPkg/PlatformPei/AmdSev.c        | 7 +++++++
 4 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 7f9220ccb90a..4bcbddb95768 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -489,10 +489,6 @@
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackSize|0x4000
 !endif
 
-!if $(SECURE_BOOT_ENABLE) == TRUE
-  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy|0x00
-!endif
-
   # IRQs 5, 9, 10, 11 are level-triggered
   gPcAtChipsetPkgTokenSpaceGuid.Pcd8259LegacyModeEdgeLevel|0x0E20
 
@@ -552,6 +548,11 @@
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|100000
 !endif
 
+!if $(SECURE_BOOT_ENABLE) == TRUE
+  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy|0x00
+!endif
+
+
 ################################################################################
 #
 # Components Section - list of all EDK II Modules needed by this Platform.
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index 36c60fc19c40..e52a3bd4db9b 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -488,10 +488,6 @@
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackSize|0x4000
 !endif
 
-!if $(SECURE_BOOT_ENABLE) == TRUE
-  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy|0x00
-!endif
-
   # IRQs 5, 9, 10, 11 are level-triggered
   gPcAtChipsetPkgTokenSpaceGuid.Pcd8259LegacyModeEdgeLevel|0x0E20
 
@@ -551,6 +547,11 @@
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|100000
 !endif
 
+!if $(SECURE_BOOT_ENABLE) == TRUE
+  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy|0x00
+!endif
+
+
 ################################################################################
 #
 # Components Section - list of all EDK II Modules needed by this Platform.
diff --git a/OvmfPkg/PlatformPei/PlatformPei.inf b/OvmfPkg/PlatformPei/PlatformPei.inf
index 16a8db7b0bd2..de7434d93dc0 100644
--- a/OvmfPkg/PlatformPei/PlatformPei.inf
+++ b/OvmfPkg/PlatformPei/PlatformPei.inf
@@ -41,6 +41,7 @@
   IntelFrameworkModulePkg/IntelFrameworkModulePkg.dec
   MdePkg/MdePkg.dec
   MdeModulePkg/MdeModulePkg.dec
+  SecurityPkg/SecurityPkg.dec
   UefiCpuPkg/UefiCpuPkg.dec
   OvmfPkg/OvmfPkg.dec
 
@@ -96,6 +97,7 @@
   gEfiMdeModulePkgTokenSpaceGuid.PcdPropertiesTableEnable
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable
   gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask
+  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy
   gUefiCpuPkgTokenSpaceGuid.PcdCpuLocalApicBaseAddress
   gUefiCpuPkgTokenSpaceGuid.PcdCpuMaxLogicalProcessorNumber
   gUefiCpuPkgTokenSpaceGuid.PcdCpuApInitTimeOutInMicroSeconds
diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c
index 26f7c3fdbb13..1539e5b5cdce 100644
--- a/OvmfPkg/PlatformPei/AmdSev.c
+++ b/OvmfPkg/PlatformPei/AmdSev.c
@@ -59,4 +59,11 @@ AmdSevInitialize (
   ASSERT_RETURN_ERROR (PcdStatus);
 
   DEBUG ((DEBUG_INFO, "SEV is enabled (mask 0x%lx)\n", EncryptionMask));
+
+  //
+  // Set Pcd to Deny the execution of option ROM when security
+  // violation.
+  //
+  PcdStatus = PcdSet32S (PcdOptionRomImageVerificationPolicy, 0x4);
+  ASSERT_RETURN_ERROR (PcdStatus);
 }
-- 
2.9.5